Credit: The Associated Press

FILE- In this June 6, 2017, file photo, a man checks his phone in an alley in downtown Chicago. A security researcher says a website flaw at a U.S. company could have allowed anyone to pinpoint the location of nearly any cellphone in the United States. The lapse at LocationSmart, a company that gathers real-time data on cellular wireless devices, is the latest to highlight how little protection consumers have from trafficking in data about their location. (AP Photo/G-Jun Yam, File)

A website flaw at a California company that gathers real-time data on cellular wireless devices could have allowed anyone to pinpoint the location of any AT&T, Verizon, Sprint or T-Mobile cellphone in the United States to within hundreds of yards, a security researcher said.

The company involved, LocationSmart of Carlsbad, California, operates in a little-known business sector that provides data to companies for such uses as tracking employees and texting e-coupons to customers near relevant stores.